It has been known to deburr and finish parts by machines known as disk finishing machines. Typical machines are shown, for example, in U.S. Pat. Nos. 4,096,666, 4,177,608, Japanese Patent 4,636,137 (1968), United Kingdom Patent 1,166,864, and USSR Patents 452,481 (1974), 058099 (1977), and 0,942,960 (1982).
In such systems, media (plastics, ceramics, etc.) and parts to be finished are contained in a finishing chamber, comprised of a rotating disk or rotor and a stationary, upstanding sidewall. As the disk or rotor rotates, centrifugal force exerts pressure on the combined media and parts on the stationary sidewall, where gravity stalls the mass and the mass falls toward the center of the rotor or disk. The continuing rotation of the rotor or disk provides a continuous cascading action of the mass toward center, as well as advance of the mass about the perimeter of the finishing chamber.
The action of such machines is a combination of the common tumbling barrel, which relies completely on the "fall" of the mass for its resulting work on parts, and the "scrubbing action" of common vibratory finishing, which features a mass of parts and media in continuous motion. The centrifugal force also accelerates the action in the finishing chamber, thereby reducing the time cycle required to finish the parts.
By using media containing many different abrasives, various finishes, from heavy deburring and material removal to very fine surface improvement, may be achieved.
A common problem of centrifugal disk finishing machines is that the rotor or disk is not supported well enough to maintain integrity at the joint or seal where the rotating disk and stationary sidewall meet.
As a result, there is a tendency for the disk to move laterally relative to the upstanding wall of the drum causing the rotor and wall to interfere with the narrow passage formed between the periphery of the rotor and wall through which the liquid normally passes, known as a seal. This causes contact and wear of the seal and interferes with the flow of liquid.
As far as the present invention is aware, no commercially process or apparatus has been developed utilizing only gaseous fluid and dry media.
Accordingly, among the objectives of the present invention are to provide a method and apparatus for finishing parts utilizing dry media wherein the rotor and wall are rigidly maintained in concentric relation under all conditions of operation and load; which incorporates a novel seal; which incorporates removable rings at the juncture of the seal; and which is easy to maintain.
In accordance with the invention, the centrifugal disk finishing apparatus utilizing dry media embodying the invention comprises a finishing chamber including an upstanding wall and a rotatable disk forming the bottom wall of the chamber. The disk is mounted in such a manner that a precision gap, known as a seal, is provided between the lower edge of the upstanding wall and the periphery of the disk. The construction of the wall and the support of the wall and disk is such that the disk and wall are rigidly maintained in concentric relation in all conditions of operation and load and therefore gaseous fluid under low pressure utilized in the finishing apparatus can flow readily from a chamber beneath the disk through the seal during operation of the apparatus.